Soybean production has become a significant force for economic development in Brazil, but has come at the cost of expansion into non-protected forests in the Amazon and native savanna in the Cerrado. Over the past fifty years, production has increased from 26 million to 260 million tons. Area planted to soybeans has increased from roughly 1 million hectares in 1970 to more than 23 million hectares in 2010, second only to the United States.
An accurate estimate of carbon fluxes associated with tropical deforestation from the last two decades is needed to balance the global carbon budget. Several studies have already estimated carbon emissions from tropical deforestation, but the estimates vary greatly and are difficult to compare due to differences in data sources, assumptions, and methodologies. In this paper, we review the different estimates and datasets, and the various challenges associated with comparing them and with accurately estimating carbon emissions from deforestation. We performed a simulation study over legal Amazonia to illustrate some of these major issues. Our analysis demonstrates the importance of considering land-cover dynamics following deforestation, including the fluxes from reclearing of secondary vegetation, the decay of product and slash pools, and the fluxes from regrowing forest. It also suggests that accurate carbon-flux estimates will need to consider historical land-cover changes for at least the previous 20 years. However, this result is highly sensitive to estimates of the partitioning of cleared carbon into instantaneous burning vs. long-timescale slash pools. We also show that carbon flux estimates based on 'committed flux' calculations, as used by a few studies, are not comparable with the 'annual balance' calculation method used by other studies.
The Jerry Yang and Akiko Yamazaki
Environment and Energy Building
Stanford University
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roz@stanford.edu
Senior Fellow, Stanford Woods Institute and Freeman Spogli Institute for International Studies
William Wrigley Professor of Earth System Science
Senior Fellow and Founding Director, Center on Food Security and the Environment
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PhD
Rosamond Naylor is the William Wrigley Professor in Earth System Science, a Senior Fellow at Stanford Woods Institute and the Freeman Spogli Institute for International Studies, the founding Director at the Center on Food Security and the Environment, and Professor of Economics (by courtesy) at Stanford University. She received her B.A. in Economics and Environmental Studies from the University of Colorado, her M.Sc. in Economics from the London School of Economics, and her Ph.D. in applied economics from Stanford University. Her research focuses on policies and practices to improve global food security and protect the environment on land and at sea. She works with her students in many locations around the world. She has been involved in many field-level research projects around the world and has published widely on issues related to intensive crop production, aquaculture and livestock systems, biofuels, climate change, food price volatility, and food policy analysis. In addition to her many peer-reviewed papers, Naylor has published two books on her work: The Evolving Sphere of Food Security (Naylor, ed., 2014), and The Tropical Oil Crops Revolution: Food, Farmers, Fuels, and Forests (Byerlee, Falcon, and Naylor, 2017).
She is a Fellow of the Ecological Society of America, a Pew Marine Fellow, a Leopold Leadership Fellow, a Fellow of the Beijer Institute for Ecological Economics, a member of Sigma Xi, and the co-Chair of the Blue Food Assessment. Naylor serves as the President of the Board of Directors for Aspen Global Change Institute, is a member of the Scientific Advisory Committee for Oceana and is a member of the Forest Advisory Panel for Cargill. At Stanford, Naylor teaches courses on the World Food Economy, Human-Environment Interactions, and Food and Security.
